Prenatal diagnosis provides valuable information on the health of the unborn child and can include invasive and non-invasive methods. The first reliable genetic diagnosis using amniocentesis was performed by Steele and Nerg in 1996. Later, first trimester chorionic villus sampling (CVS) was shown to be a safe and reliable approach for earlier prenatal diagnosis. Although both are invasive techniques and harbour potential risks of foetal miscarriage they are still considered to be the gold standards of prenatal diagnosis. Hence, these are slowly being replaced by the non-invasive prenatal diagnosis (NIPD) methods wherein foetal cells/genetic material obtained from maternal circulation are being utilized for prenatal diagnosis. In particular, identification of cell-free DNA, mRNA and foetal cells in the maternal circulation made the possibility of NIPD for diagnosis of chromosomal anomalies and single gene defects of the foetus. However, the foetal genetic materials obtained from the maternal circulation are rather insufficient to provide reliable information on chromosomal abnormalities. In particular, the cell-free DNA in maternal circulation is rather insufficient to provide complete chromosomal information such as aneuploidies for diagnosis and is also expensive. On the other hand, the foetal cells are promising candidates for detecting chromosomal abnormalities but their cell numbers are very few. In particular, the utilization of foetal cells circulating in the maternal blood is both promising for detection of aneuploidies as well as in providing complete genetic information of the foetus. Here again the major limitations are their scarcity in maternal circulation and lack of efficient separation techniques. Moreover, some of these cells might persist from previous pregnancy and may not be indicative of the current foetal status.
It is well known that prenatal diagnosis enables early identification of congenital birth defects and other risk factors that impair foetal survival, which in turn helps early intervention thereby avoiding complications and relieving parent anxiety. Of the various methods that are currently available, a diagnosis on isolated human primitive foetal erythroblasts (hPFEs) in the maternal circulation would be the most reliable and non-invasive strategy. This is because hPFEs have unique identification markers and their presence is definitely indicative of the current pregnancy and hence considered a potential candidate for early first trimester NIPD.
However, there are certain hurdles/problems that may be routinely encountered that need to be addressed to facilitate future-NIPD, and they are, (1) the numbers of circulating hPFEs in maternal circulation are very few and it is technically difficult to isolate these cells, (2) even upon successful isolation, these cells may not survive for long in the transport medium and may degenerate within a short period of time, thereby further limiting the possibility of screening for congenital defects and (3) hPFEs have very tightly condensed nuclei, and it is difficult to stimulate these cells to either prolong their life by in vitro culture or proliferate to get adequate cell numbers for future NIPD.
In view of the scarcity of foetal erythroblasts, to date no method has successfully identified and/or isolated foetal erythroblasts. Studies on foetal erythroblasts have relied only on heterogenous culture of cells, which may not provide accurate information in view of maternal cells or other impurities. Poor in vitro viability of foetal erythroblasts also severely limits the possibility of performing further analysis or studies on these cells.
Accordingly, there is a need in the art for a method for detecting, isolating and/or culturing foetal erythroblasts obtained by invasive or non-invasive means that alleviates at least one of the problems mentioned above and provides methods as potential reliable approaches for future NIPD using foetal cells present in maternal blood.